Power Conversion Device Direct Capacitor Terminal Wiring
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Solution Overview
Problem
Conventional power conversion devices with a CI configuration experience increased losses and overvoltage issues due to resonance phenomena and backflow currents between capacitors, requiring separate wiring that can lead to element breakage.
Innovation Solution
A power conversion device with a capacitor unit that accumulates DC power between the converter and inverter, where conductors are directly connected to the capacitor terminals of both modules, eliminating the need for separate wiring and reducing inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate wires are used to connect capacitors in a CI configuration, then electrical connection between converter and inverter is achieved, but wiring inductance causes resonance phenomena and backflow current increasing loss
Solution Approach 1:
The patent merges the capacitor units of the converter and inverter into a single shared capacitor unit, eliminating the need for separate connection wires between them. This integration removes the wiring inductance that causes resonance and backflow current, thereby reducing DC section loss while maintaining reliable electrical connection.
Solution Approach 2:
The patent extracts the problematic wiring inductance from the system by eliminating the separate connection wires between capacitors. By taking out the intermediate connection elements, the design directly connects the capacitor terminals, removing the source of resonance and energy loss.
2Ease of manufacture
If separate wires are provided in the DC section, then capacitor connection is established, but L(dI/dt) overvoltage occurs causing element breakage
Solution Approach 1:
The patent combines the capacitor units into a single shared unit with direct terminal connections, eliminating the separate wires that cause L(dI/dt) overvoltage. This merging approach maintains ease of manufacture through standardized direct connections while protecting elements from breakage by removing the inductance source.
3Loss of energy
If a shared capacitor unit with direct conductor connections is used, then wiring inductance is reduced eliminating resonance and backflow current, but the terminal connection configuration becomes more complex
Solution Approach 1:
The patent segments the shared capacitor unit into distinct first and second capacitor terminals that can be independently connected to the converter and inverter respectively. This segmentation allows direct conductor connections from each terminal to the corresponding module, reducing wiring inductance and eliminating resonance while maintaining manageable connection complexity through clear terminal assignment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces losses in the DC section, suppresses resonance phenomena, and decreases the risk of overvoltage, thereby enhancing the reliability and efficiency of the power conversion process.
Implementation Method 1
a capacitor unit including a capacitor cell to accumulate therein the DC power obtained by conversion of the converter
Implementation Method 2
a resonance phenomenon may occur between a wiring inductance of the relevant wire and each of capacitances of the first capacitor and the second capacitor
Data Source
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AI summary
A power conversion device that constitutes a converter-inverter unit 14 where a converter 10 to convert AC power to DC power and an inverter 12 to convert DC power obtained by conversion of the converter 10 to AC power are connected in series, in which a capacitor unit 11 including a capacitor cell 11a to accumulate therein the DC power obtained by conversion of the converter 10 is provided between the converter 10 and the inverter 12, a first conductor electrically connected to one of electrodes of the capacitor cell 11a and a second conductor electrically connected to the other electrode of the capacitor cell 11a are drawn out from the capacitor unit 11, and the first conductor is connected directly to positive-side capacitor connection terminals PCT1 and PCT2 of the converter 10 and positive-side capacitor connection terminals PIT1, PIT2, and PIT3 of the inverter 12, and the second conductor is connected directly to negative-side capacitor connection terminals NCT1 and NCT2 of the converter 10 and negative-side capacitor connection terminals NIT1, NIT2, and NIT3 of the inverter 12.